Computer systems typically employ a motherboard or backplane to which are connected a plurality of individual cards or blades. Cards typically carry a variety of different components such as central processing chips, IO devices, passive electronics and the like. Blades typically include such components as switches, routers, hard disk drives, modems, complete systems on a card and the like. The components of both cards and blades generate large amounts of heat that must be dissipated. Such systems typically include a forced air cooling system in which fans direct cooling air across the cards or blades.
In one known system, flow-blocking cards are used to completely block air flow across or through an otherwise open or empty slot or bay. By blocking the air flow across the empty slot or bay, air flow is increased adjacent to those slots or bays containing heat generating cards or blades.